Mastication of food is a key preliminary to effective nutrient extraction, and the time and energy invested in chewing have been shown to vary with food type and dentitional pattern. Food reduction involves complex three-dimensional movements of the mandible. Food is reduced by being passed across the triturating surface when the teeth are nearest occlusion; movements of the tongue and the whole head move the bolus along the tooth row. The forces required to maintain the mandible in its path consequently vary. Control of the cycle involves matching muscular activity to the demands at different parts of the cycle, reflecting in part the position, size and consistency of the food. It is proposed to correlate movements and motor sequences in three mammals and three reptiles, using wild animals, which have been conditioned to feed normally. Analysis will involve motion recording by cinematography, cinefluoroscopy, and strain gauge recording; the fiber types of the muscle will be characterized by histochemical assay, and fiber lengths and architecture determined, and their function during mastication noted by electromyography. From these data we hope to match muscle physiology and activity to those aspects that seem to be maximized, and presumably most significant to the organism.